What happened?

The documentation states that

For providers with partial OpenAI compatibility, use the compat field.
<snip>

Field	Description
openRouterRouting	OpenRouter provider routing preferences. This object is sent as-is in the provider field of the OpenRouter API request.

However, in reality the provider field is only sent if baseUrl contains "openrouter.ai":

There are cases, when baseUrl could be different from "openrouter.ai", but sending the provider field should still be sent:

1. Some LLM providers support many options from the OpenRouter API extensions (including the provider object), not just the ai-sdk/openai-compatible subset.

2. It's possible that baseUrl points to a proxy / gateway of some kind that eventually forwards the requests to openrouter.ai. In that case, checking model.baseUrl.includes("openrouter.ai") doesn't make sense.

Steps to reproduce

1. Run a local HTTP server that simply logs all HTTP requests before forwarding them to openrouter.ai.

2. Use the following models.json:

   {
       "providers": {
           "local-openrouter-proxy": {
               "baseUrl": "http://127.0.0.1:8000/api/v1",
               "api": "openai-completions",
               "apiKey": "whatever",
               "models": [
                   {
                       "id": "deepseek/deepseek-v4-pro",
                       "compat": {"openRouterRouting": {"only": ["DeepSeek"], "allow_fallbacks": false}}
                   }
               ]
           }
       }
   }

3. Observe the fact that pi silently ignores the openRouterRouting key (no provider object is inserted into the requests).

Expected behavior

The openRouterRouting key should always insert a provider object into the request, no matter what baseUrl is.

I am temporarily working around this issue with this extension:

import type { ExtensionAPI } from "@earendil-works/pi-coding-agent";

export default function (pi: ExtensionAPI) {
    pi.on("before_provider_request", (event, ctx) => {
        const provider = ctx.model?.compat?.openRouterRouting;
        if (provider !== undefined) {
            return { ...event.payload, provider };
        }
    });
}

But ideally, I think, this should be fixed in pi itself.

Version

0.76.0